Let's divide 21782587 by 408
The aim is to understand the frequency of 408 in 21782587.

Step 1:
The number 408 fits into 2 0 times, leaving a remainder of 2.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
Deduct 0 from 2 and we're left with 2.
Include the next digit (1) from the dividend after 2, then repeat: 21 / 408

On to step 2:
21 divided by 408 is 0 with a remainder of 21.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
If we subtract 0 from 21, we get 21.
Include the next digit (7) from the dividend after 21, then repeat: 217 / 408

Advancing to step 3:
217 divided by 408 is 0 with a remainder of 217.
The next digit of our result is 0. 
Result so far: 0.0
Deduct 0 from 217 and we're left with 217.
Include the next digit (8) from the dividend after 217, then repeat: 2178 / 408

Step 4:
When dividing 2178 by 408, we get 5 with a remainder of 138.
Write down 5 as next digit of the result. 
Result so far: 5.0
Deduct 2040 from 2178 and we're left with 138.
Take the next digit (2) from the dividend and append it to 138, then repeat: 1382 / 408

Going ahead to step 5:
When dividing 1382 by 408, we get 3 with a remainder of 158.
The next digit of our result is 3. 
Result so far: 53.0
The remainder is 158 after subtracting 1224 from 1382.
Bring next digit (5) of the dividend behind the 158 and repeat the process: 1585 / 408

On to step 6:
If we divide 1585 by 408, we get 3 and a remainder of 361.
The number 3 becomes the next digit in our result. 
Result so far: 533.0
Subtracting 1224 from 1585 leaves us with 361.
Bring next digit (8) of the dividend behind the 361 and repeat the process: 3618 / 408

Step 7:
The number 408 fits into 3618 8 times, leaving a remainder of 354.
Put 8 as the next digit of the answer. 
Result so far: 5338.0
Deduct 3264 from 3618 and we're left with 354.
Include the next digit (7) from the dividend after 354, then repeat: 3547 / 408

Advancing to step 8:
The number 408 fits into 3547 8 times, leaving a remainder of 283.
The number 8 becomes the next digit in our result. 
Result so far: 53388.0
Deduct 3264 from 3547 and we're left with 283.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2830, and continue the process.

On to step 9:
When dividing 2830 by 408, we get 6 with a remainder of 382.
The number 6 becomes the next digit in our result. 
Result so far: 53388.6
If we subtract 2448 from 2830, we get 382.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3820, and continue the process.

Moving on to step 10:
When dividing 3820 by 408, we get 9 with a remainder of 148.
Use 9 as the next digit of our solution. 
Result so far: 53388.69
Subtract 3672 from 3820 to get 148.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1480, and continue the process.

Moving on to step 11:
408 goes into 1480 3 times with a remainder of 256.
Record the quotient 3 as the next digit in the result. 
Result so far: 53388.693
Subtract 1224 from 1480 to get 256.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2560, and continue the process.

Going ahead to step 12:
The number 408 fits into 2560 6 times, leaving a remainder of 112.
The next digit of our result is 6. 
Result so far: 53388.6936
Subtract 2448 from 2560 to get 112.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1120, and continue the process.

Going ahead to step 13:
408 can be fit into 1120 2 times, resulting in a remainder of 304.
Put 2 as the next digit of the answer. 
Result so far: 53388.69362
If we take 816 away from 1120, we end up with 304.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3040, and continue the process.

Let's proceed to step 14:
408 goes into 3040 7 times with a remainder of 184.
The next digit of our result is 7. 
Result so far: 53388.693627
Subtract 2856 from 3040 to get 184.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1840, and continue the process.

Step 15:
408 can be fit into 1840 4 times, resulting in a remainder of 208.
Put 4 as the next digit of the answer. 
Result so far: 53388.6936274
If we take 1632 away from 1840, we end up with 208.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2080, and continue the process.

Advancing to step 16:
2080 divided by 408 is 5 with a remainder of 40.
Put 5 as the next digit of the answer. 
Result so far: 53388.69362745
The remainder is 40 after subtracting 2040 from 2080.
Since there are no more digits in the dividend, we add a zero to the remainder making it 400, and continue the process.

After the division, we end up with 53388.69362745 and a remainder of 4e-08.